Sewing machine cutting device

ABSTRACT

A cutting attachment for a sewing machine that results in severing of the thread chain immediately adjacent the sewing station, i.e., thread that has formed a stitch without being in the material or other work to be stitched. This provides significant advantages, and yet inadvertent unthreading of the sewing machine needle is effectively minimized.

IInited States Patent [191 Boser [451 Nov. 19, 1974 1 SEWING MACHINE CUTTING DEVICE [76] Inventor: Ronald J. Boser, 19 Branwood Dr.,

Dix Hills, NY. 11746 [22] Filed: Dec. 10, 1973 [211 App]. No.: 423,509

[52] 11.8. CI. 112/252 [51] Int. Cl D05b 65/00 [58] Field of Search 112/65, 68, 70, 112, 123,

[56] References Cited UNITED STATES PATENTS 6/1930 Lutz 112/252 7/1937 .lafferian 5/1945 Chudner 112/252 2,846,967 8/1958 Doerr et a1. 112/252 3,139,849 7/1964 Cohen et a1. 112/252 3,330,236 7/1967 Desormeaux 112/252 3,712,256 l/l973 Strieglek et a1 112/252 Primary Examiner-Werner l-l. Schroeder Attorney, Agent, or Firm-Bauer & Amer [57] ABSTRACT A cutting attachment for a sewing machine that results in severing of the thread chain immediately adjacent the sewing station, i.e., thread that has formed a stitch without being in the material or other work to be stitched. This provides significant advantages, and yet inadvertent unthreading of the sewing machine needle is effectively minimized.

7 Claims, 9 Drawing Figures l SEWING MACHINE CUTTING DEVICE The present invention relates to improvements for a sewing machine, and more particularly to a cutting attachment or device for such machine that achieves severing of the threads in the advantageous location immediately adjacent the sewing station.

Among other noteworthy advantages, because the separation of the work piece from the needle thread and, where applicable, also from the bobbin thread occurs adjacent the sewing station, it necessarily follows that the work piece is still under the control of the sewing machine presser foot, and otherwise is in a predictable and known location. This, in turn, greatly facilitates further handling of the work piece, as for example by stacking equipment or other such material-handling equipment. In contrast to prior art efforts to similarly achieve the foregoing, the cutting device hereof does not result in inadvertent unthreading of the sewing machine needle, i.e. inadvertent pulling of the short, severed end of the needle thread out of the eye of the needle upon start-up of the subsequent sewing interval.

Broadly, it is an object of the present invention to provide an improved sewing machine thread cutter overcoming the foregoing and other shortcomings of the prior art. Specifically, it is an object to provide a thread cutter that cuts close to the sewing station and thus provides all of the advantages attendant thereto, and yet does not adversely affect sewing operation of the machine.

A thread cutter attachment for a sewing machine demonstrating objects and advantages of the present invention includes a thread-engaging member which operates in a zone close to the sewing station, where the needle and bobbin threads are comparatively taut,

and utilizes this tautness to achieve proper engagement with these threads. Following this, the engaged threads are raised into cutting contact with a knife edge which severs these threads, appropriately in stitched engagement with the work piece, from their respective supply lengths, to thus free the work piece. Additionally, said supply lengths of thread are held, at the severing location, against being inadvertently pulled during start-up of sewing operation of the machine, and thus from resulting in unthreading of the machine.

The above brief description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative embodiment in accordance with the present invention, when taken in conjunction with the acompanying drawings, wherein:

FIG. 1 is a perspective, diagramatic view, illustrating how the needle of a sewing machine is often inadvertently unthreaded after severing of the needle thread;

FIG. 2 is an exploded perspective view of the various component parts that comprise the cutting device for a sewing machine according to the present invention;

FIGS. 3-6, inclusive, are related end elevational views illustrating the sequential movement of the component parts of the cutting device hereof which results in severing of the needle and bobbin threads; and

FIGS. 3A, 4A and 6A are side elevational views'projected respectively from FIGS. 3, 4 and 6, illustrating further structural details of the cutting device,

Reference is now made to the drawings, and in particular to FIG. 1, wherein there is shown what will be understood to be a typical sewing machine 10, the same including all the operable parts necessary to deposit chain stitching 12 in a fabric work piece 14. During a typical sewing interval, the sewing machine feed dogs 16 and the sewing machine presser foot 18, of which the lower portion has been omitted in FIG. 1 so as not to obscure structural details, cooperate to advance the work piece 14 beneath and rearwardly of the vertically reciprocating sewing machine needle 20. For reasons which are well understood, it is advantageous to sever the needle thread 22 and, where it is used, also the bobbin thread 24, as close as possible to the sewing station 20. When this is done, however, it produces a short length in the needle thread 22 and consequently, if the sewing interval happens to terminate with the thread take-up 26 in its lower or full line position as illustrated in FIG. 1, when the next sewing interval starts, the ascending movement in the take-up 26 into its raised position, as illustrated in phantom perspective in FIG. 1, will inadvertently result in the pulling of the severed end of the needle thread 22 out of the eye of the needle 20 and thus produce unthreading of the needle. It is one of the objects of the present invention to sever the threads 22, 24 in the immediate vicinity of the sewing station 20, i.e. at a location where the sewing machine needle 20 operates, and yet obviate inadvertent unthreading of the sewing machine needle 20.

The cutting device of the present invention, generally designated 30 in FIG. 2, includes those component parts illustrated in exploded perspective in FIG. 2. Specifically, to achieve the close proximate relation to the sewing machine needle 20, device 30 is supported on the sewing machine presser foot 32. More particularly it is supported on the depending body thereof which terminates in a connection, as is well understood, with the foot 34 which is in contact with the upper surface of the work piece 14, holding it in contact with the machine feed dogs 16 which urge the work piece 14 in feed movement past the sewing machine needle 20. In terms of general relationships, FIG. 2 illustrates that the cutting device 30 includes a part or main body 36 appropriately supported on the presser foot body 32. Machining in the front face thereof provides a vertically oriented slot 38 for a vertically reciprocating thread-engaging member 40. Interrupting the slot 38 is a transversally oriented compartment 42 for a block member 44 having a bottom cutting edge, as at 46. A

biasing helical spring 48 projects through a throughbore 50 into contact with the block 44 pressing it against member 40. The significance of this will be come apparent as the description proceeds. The degree of urgency in spring 48 is regulated by adjustment of threaded element 52.

As is further illustrated in FIG. 2, member 40 is actuated through vertical reciprocating movement by a lever 54 pivotally mounted, as at 56. In this connection, lever end 58 is projected through slot 60 of member 40 and terminates in a clearance slot 62 of the presser foot body 32. Further clearance or room for the pivoting movements of the lever 54 is provided by a machined compartment 64.

As illustrated in FIG. 2, member 40 includes-a lower depending portion having a cam surface 66 and, just above it, a notch 68. As a result of descending move ment of member 40, the cam surface 66 moves to one side or laterally the needle and bobbin threads 22, 24 and, in the process, actually descends below the work surface 70 of the sewing machine through the slot 72 in the presser foot 34. Stated another way, member 40 in its starting position is in an advantageous position to engage the threads. In this connection, it is also the tautness in the threads, causing the threads to snap back into place after their camming by surface 66, that also contributes to thread engagement. That is, after lateral displacement, the tautness in the threads causes them to be projected into the notch 68. When member 40 is thus raised, it is effective in lifting a loop of the needle and bobbin threads 22, 24 into cutting contact with the cutting edge 46, all as will now be explained in detail in connection with FIGS. 3-6 and the sectional views projected therefrom.

Reference is now made to FIGS. 3-6 and said sectional views, wherein the positions of movement of the thread-engaging member 40 are best illustrated. As illustrated in FIGS. 3, 3A, the starting position of member 40 is a position immediately above the needle and bobbin threads 22, 24 which will be understood to be in a substantially taut condition in what will be further understood to be an established cutting zone, generally designated 74. The tautness in the threads 22, 24 results from the feed movement of the work piece 14 rearwardly of the sewing needle while the threads 22, 24 are connected to said work piece and extend therefrom beneath member 40 to their respective supply sources 76, 78. Thus, when member 40 is urged out of slot 38 through descending movement, as should be readily appreciated upon progressive examination of FIGS. 4 and 5, the threads 22, 24 are first engaged by and cammed to one side by surface 66, and then these threads snap back, because of the tautness therein, into their original position as surface 66 continues its descent below the level of the threads and into its position as illustrated in FIG. 5. As a result of this snap-back, the threads 22, 24 project themselves within notch 68. As a consequence, when member 40 is thereafter urged through ascending movement back into its raised position, as illustrated in FIG. 6, this is effective in carrying the threads 22, 24 into cutting contact with cutting edge 46 and results in the severing of these threads.

Not only are the threads severed, but the length portions thereof are also effectively held so that inadvertent unthreading of the needle 20 does not occur. This is perhaps best illustrated in FIG. 6A to which attention is now directed. Specifically, as already explained, the loop, generally designated 80, of the threads 22, 24 which is raised by the member 40 is severed upon contact with the edge 36, thus resulting in the severing of the threads, as at 82, from the supply lengths thereof. The supply lengths of the threads 22, 24, or at least the portions thereof which are looped over the front of the cam portion 66 of member 40 are also effectively wedged between a vertical wall 84 and the member 40, all as is clearly illustrated in FIG. 6A. As may be better understood from FIG. 4A in conjunction with FIG. 6A, the room for the wedging of the length portions 80 in the location just described is provided by lateral movement of the block member 44 against the urgency of the spring 48, and thus into the clearance'86. Spring 48, in addition to allowing back up movement of the block 44 also biases said block against the member 40 and, in turn, presses member 40 against wall 84 so that the thread lengths 80 in interposed position therebetween are firmly held in place. To allow for the slight shifting in position of the member 40, which necessarily occurs when it assumes its said FIGS. 4A and 6A positions, the lever end 58 is merely projected through the slot 60, and specifically there is no fixed interconnection used between these two components.

For completeness sake, it should be noted that the remote end of lever 54 is appropriately connected, as at 8 8, to a connecting rod of a powering solenoid 92 or the like.

From the preceding description it should be readily appreciated that the cutting device 30 hereof permits severing of the needle thread 22 and of the bobbin thread 24, if such latter thread is provided, at a location which is immediately adjacent the sewing station or location of the sewing needle 20. In this advantageous location, the work piece 14 which is separated from the threads is still under the control of the presser foot 32 and thus in a predictable location. This, in turn, greatly facilitates further handling of the work piece 14 by stacking equipment, or other such equipment. Although this advantageous location for the severing of the threads is provided by the cutting device 30, this does not result in inadvertent unthreading of the sewing needle 20 since, as clearly described herein, the severed supply end of the thread 22 is firmly held and engaged between the member 40 and the wall 84, the latter bounding the compartment 38 in which member 40 operates.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. A cutting device for a sewing machine, said sewing machine including a vertically reciprocating sewing needle operative to produce stitched engagement of a needle thread in a work piece, a supply source for said needle thread, means to advance said work piece beneath and rearwardly of said sewing needle so as to draw taut said needle thread extending from said work piece to said supply source thereof, said taut length portion of said thread establishing a cutting zone, and said cutting device operable in said cutting zone comprising a vertically oriented wall, a block member in facing relation to said wall having a bottom cutting edge thereon, a vertically reciprocating threadengaging member in interposed relation between said wall and block member operatively arranged to lift a loop of said needle thread into cutting relation with said cutting edge while positioning a length portion thereof between said thread-engaging member and said wall, and spring means biasing said thread-engaging member against said wall and into holding contact with said severed loop length therebetween, whereby following said severing of said thread inadvertent unthreading of said sewing machine needle is obviated.

2. A sewing machine cutting device as claimed in claim 1 including a supply source for bobbin thread, whereby said bobbin thread exists in adjacent position to said needle thread in said cutting zone and is severed during cutting operation of said cutting device.

3. A sewing machine. cutting device as claimed in claim 2 including a sewing machine presser foot, means mounting said cutting device on said presser foot, and means urging said thread-engaging member from a raised clearance position through descending movement into position for engaging said needle and bobbin threads preparatory to ascending movement thereof to achieve said lifting of a loop of said threads into cutting contact with said cutting edge.

4. A sewing machine cutting device as claimed in claim 3 wherein said thread-engaging member includes a cam surface in depending position thereon to move laterally said needle and bobbin threads during said descending movement thereof, and above said cam surface there is provided a notch into which said threads are projected by their own tautness, whereby said threads are raised during ascending movement of said thread-engaging member.

5. A sewing machine cutting device as claimed in claim 4 wherein said block member is movable laterally in relation to said vertical movement of said threadengaging member, and said spring means is disposed in biasing relation against said block member on the side thereof remote from said wall.

6. A cutting device for a sewing machine, said sewing machine including a vertically reciprocating sewing needle operative to produce stitched engagement of needle and bobbin threads in a work piece, separate supply sources for said needle and bobbin threads, and a presser foot to assist in the advancement of said work piece beneath and rearwardly of said sewing needle so as to draw taut said needle and bobbin threads extendsources thereof, said taut length portions of said threads establishing a cutting zone, and said cutting device operable in said cutting zone comprising housing means supported on said presser foot including a vertically oriented wall, a laterally movable block member in facing relation to said Wall having a bottom cutting edge thereon, a vertically reciprocating member in interposed relation between said wall and block member having a thread-engaging notch therein, means urging said member from a raised clearance position through descending movement into position for engaging said needle and bobbin threads in said notch preparatory to ascending movement thereof to achieve the lifting of a loop of said threads into cutting contact with said cutting edge while positioning a length portion of the loop of said threads between said member and said wall, and a spring disposed in biasing relation against said block member on the side thereof remote from said wall so as to cause holding engagement of said severed loop length between said member and said wall, whereby following said severing of said threads inadvertent unthreading of said sewing machine needle is obviated.

7. A sewing machine cutting device as claimed in claim 6 wherein said member engaging said threads includes a cam surface in depending position thereon to move laterally said needle and bobbin threads during said descending movement thereof. 

1. A cutting device for a sewing machine, said sewing machine including a vertically reciprocating sewing needle operative to produce stitched engagement of a needle thread in a work piece, a supply source for said needle thread, means to advance said work piece beneath and rearwardly of said sewing needle so as to draw taut said needle thread extending from said work piece to said supply source thereof, said taut length portion of said thread establishing a cutting zone, and said cutting device operable in said cutting zone comprising a vertically oriented wall, a block member in facing relation to said wall having a bottom cutting edge thereon, a vertically reciprocating thread-engaging member in interposed relation between said wall and block member operatively arranged to lift a loop of said needle thread into cutting relation with said cutting edge while positioning a length portion thereof between said thread-engaging member and said wall, and spring means biasing said thread-engaging member against said wall and into holding contact with said severed loop length therebetween, whereby following said severing of said thread inadvertent unthreading of said sewing machine needle is obviated.
 2. A sewing machine cutting device as claimed in claim 1 including a supply source for bobbin thread, whereby said bobbin thread exists in adjacent position to said needle thread in said cutting zone and is severed during cutting operation of said cutting device.
 3. A sewing machine cutting device as claimed in claim 2 including a sewing machine presser foot, means mounting said cutting device on said presser foot, and means urging said thread-engaging member from a raised clearance position through descending movement into position for engaging said needle and bobbin threads preparatory to ascending movement thereof to achieve said lifting of a loop of said threads into cutting contact with said cutting edge.
 4. A sewing machine cutting device as claimed in claim 3 wherein said thread-engaging member includes a cam surface in depending position thereon to move laterally said needle and bobbin threads during said descending movement thereof, and above said cam surface there is provided a notch into which said threads are projected by their own tautness, whereby said threads are raised during ascending movement of said thread-engaging member.
 5. A sewing machine cutting device as claimed in claim 4 wherein said block member is movable laterally in relation to said vertical movement of said thread-engaging member, and said spring means is disposed in biasing relation against said block member on the side thereof remote from said wall.
 6. A cutting dEvice for a sewing machine, said sewing machine including a vertically reciprocating sewing needle operative to produce stitched engagement of needle and bobbin threads in a work piece, separate supply sources for said needle and bobbin threads, and a presser foot to assist in the advancement of said work piece beneath and rearwardly of said sewing needle so as to draw taut said needle and bobbin threads extending from said work piece to said respective supply sources thereof, said taut length portions of said threads establishing a cutting zone, and said cutting device operable in said cutting zone comprising housing means supported on said presser foot including a vertically oriented wall, a laterally movable block member in facing relation to said wall having a bottom cutting edge thereon, a vertically reciprocating member in interposed relation between said wall and block member having a thread-engaging notch therein, means urging said member from a raised clearance position through descending movement into position for engaging said needle and bobbin threads in said notch preparatory to ascending movement thereof to achieve the lifting of a loop of said threads into cutting contact with said cutting edge while positioning a length portion of the loop of said threads between said member and said wall, and a spring disposed in biasing relation against said block member on the side thereof remote from said wall so as to cause holding engagement of said severed loop length between said member and said wall, whereby following said severing of said threads inadvertent unthreading of said sewing machine needle is obviated.
 7. A sewing machine cutting device as claimed in claim 6 wherein said member engaging said threads includes a cam surface in depending position thereon to move laterally said needle and bobbin threads during said descending movement thereof. 